Global Navigation Satellite System (GNSS) receiver estimates delays in navigation signals received from multiple satellites and uses this information, in combination with the ephemeris information of the satellites, to estimate the receiver's position and time information. The more accurately the delays in the navigation signals are estimated, the more precisely the position and time information could be calculated in the receiver.
Traditional navigation signals, typically the LICA signals of Global Positioning System (GPS), are modulated using a Binary Phase Shift Keying (BPSK) modulation. A BPSK-modulated signal comprises a pseudo random code and a carrier. With the development of GPS, Galileo Navigation Satellite System and BeiDou Navigation Satellite System, the wideband binary-offset-carrier (BOC) modulated signals with the better performance, including signals modulated in BOC, AltBOC, ACEBOC, TD-AltBOC, TMBOC and CBOC, etc., are adopted for the next generation of navigation signals. In these modulated signals, a sub-carrier is introduced based on the traditional BPSK-modulated signals to achieve the split spectrum feature.